I do not typically associate a pontil style with a country. I find it can be an identifier for a particular company if you are trying to narrow it down within a country or region. I find it can also be used to eliminate particular makers in some cases, depending on the style, period and region you feel a piece is from.
Others may have a different opinion than mine, but that is what I have found, in my limited experience, to be more often true than not....
As far as the vase goes, I am going from memory here, but the rim is ground and gilt. There is thickness in the clear, but the iridescent surface is definitely not enamel.... My gut reaction to it was French the second I saw it, but am at a loss as to what company could have done it..... And I certainly could be wrong....
Would not be the first time... certainly will not be the last..
I have seen the surface treatment on a piece before, I just can not place when and where....
Craig